Component alignment is of critical importance in microoptical systems and especially semiconductor and/or MEMS (micro-electromechanical systems) based optical system manufacturing. The basic nature of light requires that light generating, transmitting, and modifying components must be positioned accurately with respect to one another, especially in the context of free-space-interconnect optical systems, in order to function properly and effectively. Scales characteristic of optical semiconductor and MEMS technologies can necessitate micron to sub-micron alignment accuracy.
Consider the specific example of coupling light from a semiconductor diode laser, such as a pump or transmitter laser, to a core of a single mode fiber. Only the power that is coupled into the fiber core is usable, and the coupling efficiency is highly dependent on accurate alignment between the laser output facet and the core; inaccurate alignment can result in partial or complete loss of signal transmission through the optical system. Moreover, if polarization-maintaining fiber is used, there is an added need to rotationally align the fiber relative to the laser to maintain the single polarization characteristic of the output signal.
Other more general examples include optical amplification, receiving and/or processing systems. Some alignment is typically required between an optical signal source, such as the fiber endface, and a detector. In more complex systems, including tunable filters, for example, alignment is required not only to preserve signal power but also to yield high quality or high finesse systems through the suppression of undesirable optical modes within and without the systems.
Generally, there are two types of alignment strategies: active and passive. Typically in passive alignment of the optical components, registration or alignment features are fabricated directly on the optical elements or element mounting structures as well as on the platform to which the components are to be mounted. The components are then mounted and bonded directly to the platform using the alignment features. In active alignment, an optical signal is transmitted through the components and detected. The alignment is performed based on the transmission characteristics to enable the highest possible performance level for the system.
In the context of commercial volume manufacturing, selection between active and passive alignment, or some mix of the two, is determined based on the quality of part needed. Lower cost, lower performance devices are typically manufactured with entirely passive alignment strategies, whereas the manufacture of high performance devices typically involves at least some active alignment.
There is thus a need in optical system manufacture for the precise manipulation of optical components relative to the substrate on which, and/or module in which, they are installed. Such manipulation includes the placement, attachment, and any subsequent positional modification to achieve the specified level of alignment. These needs transcend the specific classes of alignment strategies: active and passive.
In general, according to one aspect, the invention concerns a mechanical interface between a manipulation system and an optical component. This interface comprises a handle feature formed in the optical component. This feature includes two opposed depressions in the optical component, in one embodiment. The alignment system has jaws adapted to engage the optical component at the handle in these depressions.
In specific embodiments, the depressions comprise slots that extend along the width or longitudinal length of the optical component. Presently, V-shaped slots are used.
In the preferred embodiment, the jaws each comprise an engagement tooth that has a length greater than the depth of the corresponding depression. In the preferred embodiment, the depressions are located at essentially the same height on the optical component relative to a bench, on which the optical component is installed.
According to one modification, at least one of the jaws comprises a slot for engaging an optical element, such as an optical fiber. The optical element can be installed or positioned upon the mounting structure of the optical component by the manipulation system.
In general, according to another aspect, the invention can also be characterized as a process for engaging and manipulating an optical component with a manipulation system. This process comprises closing jaws of the manipulation system to insert respective jaw teeth into depressed portions of a handle feature of the optical component, for example. The jaws are collectively actuated to manipulate the optical component relative to a bench on which the optical component is installed or another optical component.
Typically, the step of closing the jaws comprises moving the jaws toward each other to engage the optical component between the jaws. After engagement, the jaws can be moved in substantially the same direction, in tandem, to deform the optical component. In another mode of operation, the jaws are moved in counter directions relative to each other. This results in the rotation of an optical element installed on the optical component.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.